CVE-2026-48020: Traefik StripPrefix Route-Level Auth Bypass via Path Normalization

Severity: critical (CVSS 10.0 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.8% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-06-23 · updated 2026-09-02
Weakness: CWE-288

Description

Traefik is an HTTP reverse proxy and load balancer. Prior to 2.11.48, 3.6.19, and 3.7.3, there is a high severity vulnerability in Traefik's StripPrefix middleware that allows an unauthenticated attacker to bypass route-level authentication and authorization. When a public router matches on a PathPrefix rule and applies the StripPrefix middleware, a request path containing .. or its percent-encoded form %2e%2e can match the public route at routing time and then, after the prefix is stripped and the path is normalized, resolve to a path served by a separate, authenticated router. As a result, an attacker can reach protected backend paths — such as admin or internal configuration endpoints — without satisfying the authentication middleware attached to the protected router. This vulnerability is fixed in 2.11.48, 3.6.19, and 3.7.3.

Affected products

Traefik: before 2.11.48; from 3.0.0 before 3.6.19; from 3.7.0 before 3.7.3 — fixed in 2.11.48, 3.6.19, 3.7.3

How to fix

Upgrade to a fixed version: Traefik 2.11.48, 3.6.19, 3.7.3. Check the vendor advisory for mitigations.

References

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